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    <title>Document</title>
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<body>
    <div id="root"></div>
    <script type="text/babel">
         class Root extends React.Component
         {
            constructor()
            {
                super();
                this.state = {
                    message:"消息",
                }
            }

            render()
            {
                return (<div>{this.state.message}</div>);
            }


         }
         const root = ReactDOM.createRoot(document.querySelector("#root"));
         root.render(<Root/>)
    </script>
</body>
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